Process for producing unsaturated carboxylic acids

ABSTRACT

A PROCESS FOR PRODUCING UNSATURATED CARBOXYLIC ACIDS, WHICH COMPRISES OXIDIZING UNSATURATED ALDEHYDES IN THE VAPOR PHASE IN THE PRESENCE OF A CATALYST COMPRISING A CATALYTIC OXIDE SUPPORTED ON AN INERT CARRIER, SUCH CATALYTIC OXIDE CONTAINING METAL ELEMENTS IN THE ATOMIC RATIO M0:V:CU:CR:W OF 12:2-14:1-6:0-4:0-12 WITH THE PROVISO THAT CR+W IS NOT O.

United States Patent M 3,833,649 PROCESS FOR PRODUCING UNSATURATED CARBOXYLIC ACIDS Masahiro Wada, Nishinomiya, Isao Yanagisawa, Ikeda, Michikazu Ninomiya, Kobe, and Takashi Ohara, Nishinomiya, Japan, assignors to Nippon Shokubai Kagaku Kogyo Co., Ltd., Osaka, Japan No Drawing. Filed Oct. 19, 1971, Ser. No. 190,661 Int. Cl. -C07c 51/26, 57/04 US. Cl. 260-530 N 8 Claims ABSTRACT OF THE DISCLOSURE A process for producing unsaturated carboxylic acids, which comprises oxidizing unsaturated aldehydes in the vapor phase in the presence of a catalyst comprising a catalytic oxide supported on an inert carrier, such catalytic oxide containing metal elements in the atomic ratio Mo:V:Cu:Cr:W of 12:214:l6:04:012 with the proviso that Cr+W is not 0.

This invention relates to a process for producing unsaturated carboxylic acids. More specifically, the invention relates to a process for producing unsaturated carboxylic acids by catalytically oxidizing unsaturated aldehydes having not less than 3 carbon atoms in the vapor phase in the presence of a catalyst, for example, a process for producing acrylic acid from acrolein, or methacrylic acid from methacrolein.

Generally, in the commercial production of unsaturated carboxylic acids by the catalytic vapor phase oxidation of unsaturated aldehydes, it is of utmost importance to use catalysts which give high conversions of the unsaturated aldehydes and high selectivities to unsaturated carboxylic acids. It is required that the catalysts should be very easily produced on a commercial basis and have stabiilty over prolonged periods of time.

Examples of the conventional catalysts for use in the production of acrylic acid or methacrylic acid by the catalytic vapor phase oxidation of acrolein or methacrolein include a catalytic oxide composed of molybdenum and vanadium as disclosed in Japanese Patent Publication No. 1,775/ 66, and a catalytic oxide composed of molybdenum, vanadium, aluminum and copper as disclosed in Japanese Patent Publication No. 26,287/69. The specification of Japanese Patent Publication No. 1,775/ 66 discloses that with the catalyst used there, the maximum one-pass yield of acrylic acid is 76.4%. Such a yield is still unsatisfactory for commercial operation. According to the specification of Japanese Patent Publication No. 26,287/ 69, the yield of acrylic acid can be 9797.5% at a space velocity of 500 to 1000 hrrl when aluminum sponge is used as a carrier and the catalyst is used in a strongly reduced condition by pre-treatment (in a state where oxygen is insufiicient). However, when the space velocity is reduced to 2000 hl. the yield abruptly goes down to 89.5%. In addition, the pretreatment for strongly reducing the catalysts includes a step of treating the catalyst with a reaction gas at a temperature higher than the reaction temperature, and therefore, various difficulties are encountered.

Accordingly, an object of the present invention is to provide a process for producing unsaturated carboxylic acids, which can be operated on a commercial basis using a novel catalyst.

'It has now been found that by using a catalytic oxide comprising molybdenum, vanadium, copper, chromium, and/or tungsten, and oxygen supported on an inert carrier, unsaturated carboxylic acid, for example acrylic acid or methacrylic acid can be obtained in very high one-pass yields from unsaturated aldehydes, for example acrolein or methacrolein, and the above object of the present invention can be achieved.

Patented Sept. 3, 1974 The catalytic oxide used in the present invention is characterized in that the metallic elements which constitute it are present in the following atomic ratios:

(with the proviso Cr+W O). Oxygen in the catalytic oxide need not be present in a specially reduced condition. It is assumed that oxygen is present in the catalytic oxide in the form of a complex metal oxide or metal acid salt. Therefor, the amount of oxygen present in the catalytic oxide varies according to the atomic ratios of the metal elements that constitute the catalytic oxide.

As the inert carrier for supporting the catalytic oxide in the present invention, natural, inert porous substances, may be exemplified, or inert porous substances. Specific examples include alpha-alumina, silicon carbide, pumice, silica, zirconia, titanium oxide, or mixtures of these. The inert carrier that is conveniently used in the present invention has a surface area of not more than 2 m. /g. and a porosity of 30 to 65%, at least of the pores having a pore diameter in the range of 50 to 1500 microns.

The catalyst used in the present invention can be prepared for example by adding an aqueous solution of ammonium bichromate and an aqueous solution of copper nitrate to an aqueous solution containing ammonium molybdate, ammonium paratungstate, and ammonium metavanadate, pouring a carrier material into the mixture, heating the mixture to evaporate it to dryness and thereby to deposit the compounds on the carrier, if desired molding it into tablets for instance, and then calcining it at 350-600 C. Any compound which can form a catalytic oxide by calcination such as hydroxides or carbonates can be used as materials for the production of the catalysts.

The catalytic vapor phase oxidation process of the present invention can be performed by passing a gaseous mixture consisting of 1 to 10% by volume of an unsaturated aldehyde (for example, acrolein, or methacrylein), 5 to 15% by volume of molecular oxygen, 20 to 60% by volume of steam, and 20 to 50% by volume of an inert gas over the catalyst prepared as above described, at a temperature of 200 to 350 C. and a pressure of atmospheric pressure to 10 atmospheres. The space velocity is maintained at 500 to 5000 hrr- The reaction can be carried out either in a fixed bed or in a fluidized bed.

According to the present invention, the one-pass yield of the unsaturated carboxylic acid can be maintained high without a decrease in the space velocity. While not wishing to be limited by any theory, it is assumed that this is perhaps because the catalytic activity is regulated by the bonding of complete oxides of copper, chromium, and tungsten or acid salts With the Mo-V system, and that it is controlled by the porosity of the carrier.

The invention Will be described in detail by the following Examples and Comparative Examples which are presented for illustrative, rather than limitative, purposes.

The conversion, selectivity, and one-pass yield used in the present specification and claims are defined as follows:

Moles of an unsaturated carboxylic acid produced Moles of an unsaturated aldehyde reacted X One-pass yield (percent) Moles of an unsaturated carboxylic acid produced Moles of an unsaturated aldehyde fed X100 EXAMPLE 1 Comparative Example 2 While 5000 ml. of water were being heated with stirring, The procedure of Exmple 1 was repeated except that 104 g. of ammonium paratungstate, 86 g. of ammonium ammonium paratungstate and ammonium bichromate metavanadate, 338 g. of ammonium molybdate, and 12 were not used. As a result a catalyst in which a catalytic g. of ammonium bichromate were added to the water. 5 oxide having a metal element composition of Separately, an aqueous solution of 86 g. of copper nitrate M0 V Cu in 300 ml. of water was prepared, and mixed with the 12 aqueous solution obtained above. The mixed solution deposited on alpha-alumina was obtained. Using this obtained was put into a porcelain evaporator on a warm catalyst, the reaction was performed under the same bath, and 1000 ml. of particulate alpha-alumina having a 10 conditions as set forth in Example 1. The results obtained diameter of 3 to 5 mm. (surface area 1 m. /g. or less, are given in Table 1.

TABLE 1 Acrylic Atomic ratio of metal ele- Acrolein acid seiec- Acrylic acid merits in catalytic oxide Reaction Space convertivity one-pass temperavelocity sion (moi (moi yield (moi M0 V Cu Cr W ture( C.) (inn- (percent) percent) percent) Examplel 12 4.6 2.2 0.5 2.4 220 1, 000 100 98.0 98.0 240 2, 000 09. 5 9s. 0 e7. 5 260 3, 000 99. 0 0s. 2 97. 2

Comparative Examplel 12 4.6 0 O 0 220 1,000 49.5 40.0 19.8 240 2, 000 45. 0 4e. 5 20. 0 260 3, 000 38. 0 51. 0 10. 4

Comparative Example2 12 4.6 2.2 0 O 220 1,000 54.6 92.0 50.2 240 2, 000 46. a 93. 0 4s. 1 260 3, 000 40. 0 93. 0 37. 2

porosity 42%, and 92% of the pores being of a pore EXAMPLES 2 AND 3 f l 75-2150 microns) were added as a Gama h Using the same catalyst as set forth in Example 1, the stirring, the mixture was evaporated to dryness to deposit reaction was performed under the Same Conditions as me compounds on carrier: and h cfflcmed for in Example 1 except that the space velocity was changed hours at 400 C. As a result a catalyst in which a catalytlc to 00 -1 (Example 2) and 5000 -1 (Example OXidfi having a metal element composition Of The results are given in Table 2 be10 TAB LE 2 12 4=.6 2.2 0.6 2.4

R t cqnverr' s 1 t t iii i 1 i deposited on the alpha-alumina carrier was obtained- Space raging; ai lefn Zrein a ryliiz velocity ture mole acid (mole acid mole One thousand mlllllitfils of the resulting catalyst were Examples (MP1) (0 a) Descent) percent) pecem) packed mto a U-shaped stainless steel tube having a diameter of 25 cm., and the tube was immersed in a molten 4.0 3:323 i883 37 8 3 13 82:3 nitrate bath heated at 220260 C. A gaseous mixture consisting of 4% of acrolein, 55% of air, and 41% of EXAMPLES 4 6 steam, all by volume, was fed into the tube, and reacted The procedure f Example 1 was repeated except that at a Space Velocity of 1000 to 3000 The results r the composition of the gaseous mixture was changed. obtained are shown in Table 1. The results obtained are given in Table 3.

TABLE 3 Composition of One-pass gaseous mixture Selectivity yield of (vol. percent) Reaction Conversion of acrylic acrylic tempera- Space of acrolein acid acid Acroture velocity (mol (mole (mole Examples lein Air Steam C.) (lirr percent) percent) percent) 5 55 270 4, 000 98.0 07.7 95.8 e 54 40 255 s, 000 90. 0 07. 0 96. 0 s 02 30 205 s, 000 98. 5 06. 1 94. 7

Comparative Example 1 EXAMPLES 7 TO 9 The procedure of Example 1 was repeated except that The procedure of Example 1 was repeated except that ammonium paratungstate, ammonium bichromate, and a different carrier was used. The results are given in copper nitrate were not used. As a result a catalyst in 00 Table 4.

TABLE 4 Physical properties of the carrier Conver- Selec- One-pass Reaction sion of tivity of yield of Surface 'tcmpera- Space acrolein acrylic acrylic area Porosity Pore ture velocity (moi acid (moi acid (moi Example Carrier (mi/g.) (percent) distribution C.) (hrr percent) percent) percent) 7 Siliconcarbide 1 55 -50Qu,93% 230 2,000 09.0 98.0 97.0 a-Alllnlina (50%) silicon carbide. 1 47 75l,00u,95% 230 2,000 99.0 98.0 07.0 9 rat-Alumina (75%) silica 1 40 501,200u,95% 230 2,000 98.0 98.0

which a catalytic oxide having a metal element composi- EXAMPLES 10 TO 14 tion Mo V deposited on the alpha-alumina carrier was obtained. Using this catalyst, the reaction was per- The procedure of Example 1 was repeated except that formed under the same conditions as set forth in Example the atomic ratio of metal elements in the catalytic oxide 1. The results obtained are given in Table 1. 79 was varied. The results obtained are given in Table 5.

TABLE 5 Atomic ratio of metal One-pass elements in the Reaction Conversion Selectivity yield of catalytic oxide tempera- Space of acrolein of acrylic acrylic ture velocity (mol acid (mol acid (mol Example Mo V Cu Cr W 0.) (hr.- percent) percent) percent) The results obtained in Examples 1 to 14 above demonstrate that the reaction can be performed under a wide range of conditions without reducing the yield of acrylic acid.

EXAMPLE 15 Using the same catalyst and apparatus as used in Example 1, a gaseous mixture consisting of 4% by volume of methacrolein, 51% of air, and 45% of steam was reacted at 340 C. and a space velocity of 2000 hr. The conversion of methacrolein was 70%; the selectivity of methacrylic acid was 75.5%; and the one-pass yield of methacrylic acid was 52.8%.

What is claimed is:

1. A process for producing unsaturated carboxylic acids, which comprises oxidizing unsaturated aldehydes in the vapor phase in the presence of a catalyst comprising a catalytic oxide supported on an inert carrier, said catalytic oxide consisting essentially of the recited metal elements in the atomic ratio Mo:V:Cu:Cr:W of 12:214:16:04:012 with the proviso that Cr+W is not 0, said inert carrier having a surface area not greater than 2 mF/g. and a porosity of 30 to 65%, at least 90% of the pores having a pore diameter in the range of 50 to 1500 microns.

2. A process for producing unsaturated carboxylic acids, which comprises oxidizing unsaturated aldehydes in the vapor phase at 200 to 350 C. and normal atmospheric pressure to 10 atmospheres in the presence of a catalyst comprising a catalytic oxide supported on an inert carrier, said catalytic oxide consisting essentially of the recited metal elements in the atomic ratio Mo:V:Cu:Cr:W of 12:214:16:0 4:012 with the proviso that Cr-i-W is not 0, said inert carrier having a surface area not greater than 2 m. /g. and a porosity of 30 to 65%, at least 90% of the pores having a pore diameter in the range of 50 to 1500 microns.

3. A process for producing acrylic acid, which comprises oxidizing acrolein with molecular oxygen in the vapor phase at 200-350 C. and normal atmospheric pressure to 10 atmospheres in the presence of a catalyst comprising a catalytic oxide supported on an inert carrier, said catalytic oxide consisting essentially of the recited metal elements in the atomic ratio Mo:V:Cu:Cr:W of 12:214:16:0-4:0-12 with the proviso that Cr+W is not 0, said inert carrier having a surface area not greater than 2 mF/g. and a porosity of 30 to 65%, at least 90% of the pores having a pore diameter in the range of to 1500 microns.

4. A process for producing methacrylic acid, which comprises oxidizing methacrolein with molecular oxygen in the vapor phase at 200 to 350 C. and normal atmospheric pressure to 10 atmospheres in the presence of a catalyst comprising a catalytic oxide supported on an inert carrier, said catalytic oxide consisting essentially of the recited metal elements in the atomic ratio Mo:V:Cu:Cr:W of 12:214:16:0-4:0-12 with the proviso that Cr+W is not 0, said inert carrier having a surface area not greater than 2 m. g. and a porosity of 30 to at least of the pores having a pore diameter in the range of 50 to 1500 microns.

5. The process of claim 1 wherein said inert carrier is selected from u-alumina, silicon carbide, pumice, silica, zirconia, titanium oxide or mixtures thereof.

6. The process of claim 2 wherein said inert carrier is selected from a-alumina, silicon carbide, pumice, silica, zirconia, titanium oxide and mixtures thereof.

7. The process of claim 3 wherein said inert carrier is selected from a-alumina, silicon carbide, pumice, silica, zirconia, titanium oxide or mixtures thereof.

8. The process of claim 4 wherein said inert carrier is selected from u-alumina, silicon carbide, pumice, silica, zirconia, titanium oxide or mixtures thereof.

References Cited UNITED STATES PATENTS 3,567,773 3/1971 Yamaguchi et al. 260-530 N 3,644,509 2/1972 Allen 260-530 N 3,775,474 11/1973 OHara et al. 260-530 N FOREIGN PATENTS 1,924,496 11/1969 Germany 260-530 N 1,007,405 10/1965 Great Britain 260-530 N 1,032,261 6/1966 Great Britain 260-530 N 1,084,143 9/1967 Great Britain 260-530 N 1,086,523 10/1967 Great Britain 260-530 N 746,202 8/1970 Belgium 260-530 N LORRAINE A. WEINBERGER, Primary Examiner RICHARD D. KELLY, Assistant Examiner US. Cl. X.R. 252-456, 464, 467

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 53, 9 Dated- September 74 Inventoflg) Masahiro Wade et a1.

It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

The term of this patent subsequent to November 27,

1990 has been disclaimed.

Signed and Scaled this Eighth Day of February 1977 [SEAL] A ttes t:

RUTH C. MASON C. MARSHALL DANN Arresting Officer Commissioner oflatenls and Trademarks UNITED STATES PATENT OFFICE CERHMCATE 0F CGRECHN .3 Patent No. v 3,833,649 v Dated September 3, 1974 Inventor(s) Masahiro WADA ET AL It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

In the Heading, insert patentees' Foreign Application Priorit Data as follows:

-- Claims priority, application Japan, October 23, 1970,

No. 45-92759/70. Signed and Emailed this twenty-third 0f March 1976 [SEAL] Arrest: Q

RUTH C. MASON C. MARSHALL DANN Arresting Offic r Commissioner of Parents and Trademarks 

